def transversal_yield_lv(sets: List[PySet], transversal: Tuple[PyValue, PyValue, PyValue]):
"""
transversal is a tuple of length len(sets).
Initially it consists of uninstaniated PyValues.
When all the PyValues are instantiated, it is yielded as the answer.
"""
remaining_indices = uninstantiated_indices_lv(transversal)
if not remaining_indices:
yield transversal
else:
if propagate:
# If we are propagating, we will have removed used values from all the sets.
# If any of those sets are now empty but are associated with
# an uninstantiated position in transversal, fail;
empty_sets = [sets[indx].is_empty() for indx in remaining_indices]
if any(empty_sets):
return None
next_index = min(remaining_indices,
key=lambda indx: indx if not smallest_first else len(sets[indx]))
# T_next is the PyValue to be instantiated this time around.
T_next = transversal[next_index]
used_values = PyList([transversal[i] for i in range(len(transversal)) if i not in remaining_indices])
for _ in member(T_next, sets[next_index]):
for _ in fails(member)(T_next, used_values):
new_sets = sets if not propagate else [set.discard(T_next) for set in sets]
yield from transversal_yield_lv(new_sets, transversal)
def all_all_distinct(lists: List[List[Term]]):
for lst in lists:
for _ in fails(all_distinct)(lst):
# Fail if any of the lists fails all_distinct.
return
# Succeed if they all succeed.
yield
def transversal_yield_lv(sets: List[PyList], so_far: PyList, Answer: Var):
print(f'sets/[{", ".join([str(S) for S in sets])}]; so_far_reversed/{reversed(so_far)}')
if not sets:
yield from unify(reversed(so_far), Answer)
else:
[S, *Ss] = sets
X = Var( )
for _ in member(X, S):
for _ in fails(member)(X, so_far):
yield from transversal_yield_lv(Ss, PyList([X]) + so_far, Answer)
def transversal_yield_lv(Sets: List[PyList], Partial_Transversal: PyList,
Complete_Transversal: Var):
print(
f'Sets/[{", ".join([str(S) for S in Sets])}]; Partial_Transversal/{Partial_Transversal}'
)
if not Sets:
yield from unify(Partial_Transversal, Complete_Transversal)
else:
(S, Ss) = (Sets[0], Sets[1:])
Element = Var()
for _ in member(Element, S):
for _ in fails(member)(Element, Partial_Transversal):
yield from transversal_yield_lv(
Ss, Partial_Transversal + PyList([Element]),
Complete_Transversal)
def tnvsl_dfs_gen_lv(sets, tnvsl):
var_indxs = uninstan_indices_lv(tnvsl)
if not var_indxs: yield tnvsl
else:
empty_sets = [sets[indx].is_empty() for indx in var_indxs]
if any(empty_sets): return None
nxt_indx = min(var_indxs, key=lambda indx: len(sets[indx]))
used_values = PyList(
[tnvsl[i] for i in range(len(tnvsl)) if i not in var_indxs])
T_Var = tnvsl[nxt_indx]
for _ in member(T_Var, sets[nxt_indx]):
for _ in fails(member)(T_Var, used_values):
new_sets = [set.discard(T_Var) for set in sets]
yield from tnvsl_dfs_gen_lv(new_sets, tnvsl)